class_docstr: Ignite handler to execute additional post processing after the post processing in engines.
  So users can insert other handlers between engine postprocessing and this post processing handler.
  If using components from `monai.transforms` as the `transform`, recommend to decollate `engine.state.batch`
  and `engine.state.batch` in the engine(set `decollate=True`) or in the `DecollateBatch` handler first.
docstr: Args:
      transform: callable function to execute on the `engine.state.batch` and `engine.state.output`.
          can also be composed transforms.
      event: expected EVENT to attach the handler, should be "MODEL_COMPLETED" or "ITERATION_COMPLETED".
          default to "MODEL_COMPLETED".
docstr_tok: ["Args",":","transform",":","callable","function","to","execute","on","the","`","engine.state.batch","`","and","`","engine.state.output","`",".","can","also","be","composed","transforms",".","event",":","expected","EVENT","to","attach","the","handler",",","should","be","``","MODEL_COMPLETED","''","or","``","ITERATION_COMPLETED","''",".","default","to","``","MODEL_COMPLETED","''","."]
code: def __init__(
      self, transform: Callable, event: str = "MODEL_COMPLETED"
  ) -> None:
      """
      Args:
          transform: callable function to execute on the `engine.state.batch` and `engine.state.output`.
              can also be composed transforms.
          event: expected EVENT to attach the handler, should be "MODEL_COMPLETED" or "ITERATION_COMPLETED".
              default to "MODEL_COMPLETED".
  
      """
      self.transform = transform
      event = event.upper()
      if event not in ("MODEL_COMPLETED", "ITERATION_COMPLETED"):
          raise ValueError(
              "event should be `MODEL_COMPLETED` or `ITERATION_COMPLETED`."
          )
      self.event = event
  
file_path: MONAI/monai/handlers/postprocessing.py
imports: from __future__ import annotations
  from collections.abc import Callable
  from typing import TYPE_CHECKING
  from monai.config import IgniteInfo
  from monai.engines.utils import IterationEvents, engine_apply_transform
  from monai.utils import min_version, optional_import
label_desc: Use image node_id 1 to create a new PostProcessing object  with example: obj = PostProcessing(transform, event)